Clue to male baldness found

Scientists have identified a stem cell defect as a key factor behind common baldness, paving the way for possible hair-loss treatments in future.

According to researchers in the United States, the process by which hair follicle stem cells turn into hair-producing progenitor cells is short-circuited by a malfunction at a cellular level.

The defect is thought to be responsible for the onset of androgenetic alopecia, an inherited form of hair loss that affects both men and women, although it rarely results in baldness in women.

While men with the condition see their hairline recede according to the familiar pattern, possibly resulting in total baldness, women will experience overall thinning of their hair.

According to co-author George Cotsarelis, chairman of the dermatology department at the University of Pennsylvania School of Medicine, the findings have boosted hopes of treatments to reverse such hair-loss.

Researchers working on baldness had previously believed that the stem cells disappeared entirely, which would have made the condition much harder to treat.

The researchers studies human scalp tissue from people who were both bald and with hair from 54 white men aged 40-65 years.

The samples had been discarded during hair transplant procedures performed on the men.

They found that both bald and haired tissue contained equivalent amounts of preserved stem cells, which give rise to progenitor cells which stimulate hair growth.

The main difference was that bald tissue did not contain the normal amount of progenitor cells, which suggested that the hair follicle stem cells were not performing normally.

Cotsarelis said the follicles in bald people become miniaturised, and only able to produce microscopic hairs.

The stem cells were for some reason blocked or incapable of making progenitor cells for hair growth, Cotsarelis said.

He said the team was surprised and encouraged by the finding, however.

Baldness affects millions of people around the world.

Writing in the Journal of Clinical Investigation, researchers said their findings might lead to new targets for treatment of baldness.

They said more research was needed to understand better how to get a stem cell to make and activate a progenitor cell, however, before new treatments could be developed.

Hair loss experts said there was still a long way to go.

According to Vicki Kalabokes, president and CEO of the National Alopecia Areata Foundation, the new research could open up an avenue for future explorations.

But she warned that decades might elapse before a treatment finally made its way to a clinical setting.